Hostname: page-component-586b7cd67f-vdxz6 Total loading time: 0 Render date: 2024-12-04T19:35:36.832Z Has data issue: false hasContentIssue false
  • English
  • Français

The Photosynthesis and Transpiration of Crops

Published online by Cambridge University Press:  03 October 2008

J. L. Monteith
J. L. Monteith
Affiliation:
Rothamsted Experimental Station, Harpenden, Herts
Get access Rights & Permissions [Opens in a new window]

Summary

When a leaf absorbs radiant energy, only a small fraction is stored chemically in photosynthesis. In sunlight, this fraction is at most one-fifth of the energy in the visible spectrum, decreasing with increasing light intensity because of the finite resistance to the diffusion of carbon dioxide through the leaf to the chloroplasts. Energy absorbed but not stored in photosynthesis is dissipated by transpiration and convection.

The potential or maximum photosynthesis of a crop canopy can be estimated from a set of six parameters describing the photosynthesis-light curve of single leaves, the arrangement of leaves in the canopy, and radiation climate. Comparing estimates of potential photosynthesis with measurements of carbon dioxide exchange over a field of sugar beet, the estimated rate of respiration was 2 gm carbohydrate per m2 leaf area per day, equivalent to 44 per cent of gross photosynthesis over the whole growing season. Over the season, the foliage lost 34 per cent of incident radiation by transmission to the soil.

The potential rate of transpiration can be found from Penman's formula assuming values of external (aerodynamic) and internal (mainly stomatal) resistance for the canopy as a whole. In south-east England, the energy for potential transpiration is almost equal to net heat H in summer and is therefore about half the energy of incoming solar radiation. For a real crop of grass subject to moisture stress, transpiration was less than the potential rate at about 0·8 H on average and 0·3 H in very dry weather.

During the summer, cumulative photosynthesis increases linearly with cumulative transpiration to give a production ratio (gross photosynthesis/transpiration) of 1/100 in the Thames Valley and 1/200 in the Sacramento Valley. The production ratio is expected to change with crop type as well as with climate.

Type
Research Article
Information
Experimental Agriculture , Volume 2 , Issue 1 , January 1966 , pp. 1 - 14
Copyright
Copyright © Cambridge University Press 1966

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

References

REFERENCES

Gaastra, P (1958). Meded. LandbHoogesch. Wageningen 58, 1.Google Scholar
Gaastra, P. (1959). Meded. LandbHoogesch. Wageningen 59, 1.Google Scholar
Gaastra, P. (1963). In ‘Environmental Control of Plant Growth’ (Ed. Evans, ). New York: Academic Press.Google Scholar
Gaffron, H. (1960). In ‘Plant Physiology 1B’ (Ed. Steward, ). New York: Academic Press.Google Scholar
Holmgren, P., Jarvis, P. G. & Jarvis, M. S. (1965). Physiologia Pl. 18, 557.CrossRefGoogle Scholar
Lawes, J. B. (1850). J. hort. Sci. 5, 38.Google Scholar
Monteith, J. L. (1958). UNESCO Arid Zone Res. 11, 123.Google Scholar
Monteith, J. L. (1962). Neth. J. agric. Sci. 10, 334.Google Scholar
Monteith, J. L. (1963). In ‘Environmental Control of Plant Growth’ (Ed. Evans, ). New York: Academic Press.Google Scholar
Monteith, J. L. (1965a). Expl. Agric. 1, 241.CrossRefGoogle Scholar
Monteith, J. L. (1965b). Fld Crop Abstr. 18, 213.Google Scholar
Monteith, J. L. (1965C). Ann. Bot., Lond. 29, 17.CrossRefGoogle Scholar
Monteith, J. L. (1965d). Symp. Soc. exp. Biol. 19, 205.Google Scholar
Monteith, J. L. & Szeicz, G. (1959). Q. Jl R. met. Soc. 86, 205.CrossRefGoogle Scholar
Monteith, J. L., Szeicz, G. & Waggoner, P. E. (1965). J. appl. Ecol. 1, 345.CrossRefGoogle Scholar
Morris, L. G. (1959). J. agric. Engng Res. 4, 161.Google Scholar
Penman, H. L. (1948). Proc. R. Soc. A. 193, 120.Google Scholar
Penman, H. L. (1955). Q.Jl R. met. Soc. 81, 507.CrossRefGoogle Scholar
Penman, H. L. (1962). J. agric. Sci. 58, 349.CrossRefGoogle Scholar
Stanhill, G. (1960). Proc. 8th Int. Grassland Cong., 293.Google Scholar
Waggoner, P. E., Monteith, J. L. & Szeicz, G. (1964). Nature, 201, 97.CrossRefGoogle Scholar
Watson, D. J. & Hayashi, K-I. (1965). New Phytol. 64, 38.CrossRefGoogle Scholar
de Wrr, C. T. (1958). Versl. landbouwk. Onderz. RijkslandbProefstn, 64.6.Google Scholar
de Wrr, C. T. (1962). Agric. Res. Rep. 663 (formerly Versl. lanbouwk. Onderz. Rijkslandb-Proefstn.)Google Scholar